x1, y1, x2, y2 = map(float, input().split())
print(((y2-y1)**2 + (x2-x1)**2)**(1/2))
 x1, y1, x2, y2 = map(float, input().split()) x1 map(float, input().split()) map float input().split() ().split () input split y1 x2 y2 print(((y2-y1)**2 + (x2-x1)**2)**(1/2)) print ((y2-y1)**2 + (x2-x1)**2)**(1/2) (y2-y1)**2 + (x2-x1)**2 (y2-y1)**2 y2-y1 y2 y1 2 (x2-x1)**2 x2-x1 x2 x1 2 1/2 1 2 y1, x2, y2 = map(float, input().split()) map(float, input().split()) y1 x2, y2 = map(float, input().split()) map(float, input().split()) x2 y2 = map(float, input().split()) map(float, input().split()) y2 x1, y1, x2, y2 = map(float, input().split()) map(float, input().split()) x1
x1, y1, x2, y2 = map(float, input().split())
print(((y2-y1)**2 + (x2-x1)**2)**(1/2))

